Added file transfer to example.
diff --git a/Doc/lib/libftplib.tex b/Doc/lib/libftplib.tex
index 00b01a7..d2358e8 100644
--- a/Doc/lib/libftplib.tex
+++ b/Doc/lib/libftplib.tex
@@ -28,6 +28,8 @@
  .
  .
  .
+>>> ftp.retrbinary('RETR README', open('README', 'wb').write)
+'226 Transfer complete.'
 >>> ftp.quit()
 \end{verbatim}